void tree_dp(int x,int father,long long max)
{
long long t1,t2,t3;
t1=v[x][0],t2=v[x][1],t3=max;
if (t3>t2)
{
long long t;
t=t2,t2=t3,t3=t;
}
if (t2>t1)
{
long long t;
t=t2,t2=t1,t1=t;
}
if (t1+2*t2+t3>ans)
ans=t1+2*t2+t3;
for (int i=b[x];i;i=a[i][2])
{
if (a[i][0]==father)
continue;
long long t;
if (f[x]!=a[i][0])
t=v[x][0];
else
t=v[x][1];
if (t>max)
tree_dp(a[i][0],x,t+a[i][1]);
else
tree_dp(a[i][0],x,max+a[i][1]);
}
}
int main (int argc, char * const argv[]) {
int n;
while (~scanf("%d",&n)) {
int root=0;
memset(head, -1, sizeof(head));
memset(isroot, true, sizeof(isroot));
cnt=0;
for (int i=1; i<=n; i++) scanf("%d",&con[i]);
for (int i=0; i<n; i++) {
int a,b;
scanf("%d %d",&a,&b);
if (a==0&&b==0)break;
isroot[a]=false;
addEdge(b, a);
}
for (int i=1; i<=n; i++)
if (isroot[i]) {
root=i;
break;
}
tree_dp(root);
printf("%d\n",max(dp[root][0],dp[root][1]));
}
return 0;
}
void work()
{
long long floodfill(int,int);
void tree_dp(int,int,long long);
int n;
scanf("%d%*d",&n);
for (int i=1;i<=n-1;i++)
{
int x,y,t;
scanf("%d%d%d",&x,&y,&t);
a[i][0]=y;
a[i][1]=t;
a[i][2]=b[x];
b[x]=i;
a[i+n][0]=x;
a[i+n][1]=t;
a[i+n][2]=b[y];
b[y]=i+n;
d[x]++;
d[y]++;
}
int root,max=0;
for (int i=1;i<=n;i++)
if (d[i]==1 && a[b[i]][1]>max)
{
root=i;
max=a[b[i]][1];
}
floodfill(root,0);
tree_dp(root,0,0);
printf("%lld\n",ans);
}
void tree_dp(int num)
{
dp[num][0]=0;
dp[num][1]=con[num];
for (int i=head[num]; i!=-1; i=e[i].next) {
tree_dp(e[i].to);
dp[num][0]+=(dp[e[i].to][1]>dp[e[i].to][0]?dp[e[i].to][1]:dp[e[i].to][0]);
dp[num][1]+=dp[e[i].to][0];
}
}
